A hybrid vehicle comprises an internal combustion engine, which transmits the torque to the driving wheels by means of a transmission provided with a gearbox, and at least one electric machine mechanically connected to the driving wheels; the electric machine is supplied by an electronic power converter connected to an electric storage system, typically consisting of a pack of chemical batteries, possibly connected in parallel to one or more super-capacitors.
In a hybrid vehicle, a cooling system is needed, which is dedicated to the electric components, i.e. the electric machine, the electronic power converter and the storage system, to avoid the electric components from overheating. With this regard, it is worth noting that, in use, all electric components are a source of electricity losses, which electricity is transformed into heat which thus should be appropriately disposed of.
Patent application US2004118142A1 describes using part of the cold generated by an air conditioning system of the passenger compartment to cool the electric components, i.e. the storage system, the electric machine, and the electronic power converter. However, using part of the cold generated by the air conditioning system of the passenger compartment has various drawbacks, because the electric components are generally arranged apart from the air conditioning system, and therefore long connection pipes, which should be appropriately insulated (and are therefore cumbersome), are needed. Moreover, because the generated cold is to be split between the cooling needs of the passenger compartment and the cooling needs of the electric components, it may occur that in case of particularly high temperatures, the available cold is insufficient for cooling the passenger compartment, and therefore passengers' comfort is compromised; in order to solve this drawback, the refrigerating power of the air conditioning system of the passenger compartment is to be increased, but such an increase is not always possible due to the limited space available for the air conditioning system of the passenger compartment. Finally, the optimal temperature of the cooling liquid for cooling the passenger compartment could be different (even very different) from the optimal temperature of the refrigeration liquid for cooling the electric components, and therefore it may be necessary to choose a compromise between the various needs for choosing the actual temperature of the cooling liquid.
Patent application WO2008151087A2 describes an electric vehicle provided with a cooling system of the storage system, which is completely independent and separate from the air conditioning system of the passenger compartment, and which may use a compression refrigeration cycle to cool the storage system itself.
Patent application US2009024256A1 describes a system for regulating the temperature of the storage system of an electric vehicle.